Conceptualization and measurement of quality of life in dementia: the dementia quality of life instrument (DQoL).

Direct assessment of quality of life (QoL) of persons with dementia has largely been ignored due to logistical, conceptual and practical issues. This article presents a disease-specific conceptual framework of QoL for dementia. Based on this conceptualization, a 29-item instrument designed to assess QoL by direct interview with dementia patients was developed and tested on 99 participants. The data show that the instrument is reliable and shows evidence of validity. Nearly all participants (96%) were able to respond to questions appropriately. Thus, persons with mild to moderate dementia can be considered good informants of their own subjective states, paving the way to consider patient responses rather than proxy measures as the gold standard for assessing QoL for persons with dementia.